============================================
WARNING: possible recursive locking detected
6.8.0-rc1-syzkaller-00385-g4854cf9c61d0 #0 Not tainted
--------------------------------------------
syz-executor.2/29207 is trying to acquire lock:
ffff88802f4ae0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff88802f4ae0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4452 [inline]
ffff88802f4ae0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1ab3/0x3ed0 net/core/dev.c:4347
but task is already holding lock:
ffff8880475480d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff8880475480d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4452 [inline]
ffff8880475480d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x333/0xc20 net/sched/sch_generic.c:340
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(_xmit_ETHER#2);
lock(_xmit_ETHER#2);
*** DEADLOCK ***
May be due to missing lock nesting notation
8 locks held by syz-executor.2/29207:
#0: ffff8880835780b0 (slock-AF_INET6/1){+.-.}-{2:2}, at: l2tp_xmit_core net/l2tp/l2tp_core.c:1044 [inline]
#0: ffff8880835780b0 (slock-AF_INET6/1){+.-.}-{2:2}, at: l2tp_xmit_skb+0x6bc/0x1940 net/l2tp/l2tp_core.c:1109
#1: ffffffff8d1acbe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
#1: ffffffff8d1acbe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
#1: ffffffff8d1acbe0 (rcu_read_lock){....}-{1:2}, at: __ip_queue_xmit+0x72/0x1a50 net/ipv4/ip_output.c:470
#2: ffffffff8d1acbe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
#2: ffffffff8d1acbe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
#2: ffffffff8d1acbe0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x364/0x2540 net/ipv4/ip_output.c:228
#3: ffffffff8d1acb80 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#3: ffffffff8d1acb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline]
#3: ffffffff8d1acb80 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x244/0x3ed0 net/core/dev.c:4276
#4: ffff888046cec258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline]
#4: ffff888046cec258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline]
#4: ffff888046cec258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:192 [inline]
#4: ffff888046cec258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3763 [inline]
#4: ffff888046cec258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x108c/0x3ed0 net/core/dev.c:4317
#5: ffff8880475480d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
#5: ffff8880475480d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4452 [inline]
#5: ffff8880475480d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x333/0xc20 net/sched/sch_generic.c:340
#6: ffffffff8d1acbe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
#6: ffffffff8d1acbe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
#6: ffffffff8d1acbe0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x364/0x2540 net/ipv4/ip_output.c:228
#7: ffffffff8d1acb80 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#7: ffffffff8d1acb80 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline]
#7: ffffffff8d1acb80 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x244/0x3ed0 net/core/dev.c:4276
stack backtrace:
CPU: 0 PID: 29207 Comm: syz-executor.2 Not tainted 6.8.0-rc1-syzkaller-00385-g4854cf9c61d0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
check_deadlock kernel/locking/lockdep.c:3062 [inline]
validate_chain kernel/locking/lockdep.c:3856 [inline]
__lock_acquire+0x210a/0x3b30 kernel/locking/lockdep.c:5137
lock_acquire kernel/locking/lockdep.c:5754 [inline]
lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
__netif_tx_lock include/linux/netdevice.h:4452 [inline]
__dev_queue_xmit+0x1ab3/0x3ed0 net/core/dev.c:4347
dev_queue_xmit include/linux/netdevice.h:3171 [inline]
neigh_resolve_output net/core/neighbour.c:1563 [inline]
neigh_resolve_output+0x584/0x8f0 net/core/neighbour.c:1543
neigh_output include/net/neighbour.h:542 [inline]
ip_finish_output2+0x82d/0x2540 net/ipv4/ip_output.c:235
__ip_finish_output net/ipv4/ip_output.c:313 [inline]
__ip_finish_output+0x38b/0x650 net/ipv4/ip_output.c:295
ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:323
NF_HOOK_COND include/linux/netfilter.h:303 [inline]
ip_mc_output+0x1dd/0x6a0 net/ipv4/ip_output.c:420
dst_output include/net/dst.h:451 [inline]
ip_local_out+0xaf/0x1a0 net/ipv4/ip_output.c:129
iptunnel_xmit+0x5b4/0x9b0 net/ipv4/ip_tunnel_core.c:82
ip_tunnel_xmit+0x1daa/0x33b0 net/ipv4/ip_tunnel.c:831
erspan_xmit+0x51f/0x1bf0 net/ipv4/ip_gre.c:720
__netdev_start_xmit include/linux/netdevice.h:4989 [inline]
netdev_start_xmit include/linux/netdevice.h:5003 [inline]
xmit_one net/core/dev.c:3547 [inline]
dev_hard_start_xmit+0x137/0x6d0 net/core/dev.c:3563
sch_direct_xmit+0x1ac/0xc20 net/sched/sch_generic.c:342
__dev_xmit_skb net/core/dev.c:3776 [inline]
__dev_queue_xmit+0x12b0/0x3ed0 net/core/dev.c:4317
dev_queue_xmit include/linux/netdevice.h:3171 [inline]
neigh_resolve_output net/core/neighbour.c:1563 [inline]
neigh_resolve_output+0x584/0x8f0 net/core/neighbour.c:1543
neigh_output include/net/neighbour.h:542 [inline]
ip_finish_output2+0x82d/0x2540 net/ipv4/ip_output.c:235
__ip_finish_output net/ipv4/ip_output.c:313 [inline]
__ip_finish_output+0x38b/0x650 net/ipv4/ip_output.c:295
ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:323
NF_HOOK_COND include/linux/netfilter.h:303 [inline]
ip_mc_output+0x1dd/0x6a0 net/ipv4/ip_output.c:420
dst_output include/net/dst.h:451 [inline]
ip_local_out net/ipv4/ip_output.c:129 [inline]
__ip_queue_xmit+0x7cb/0x1a50 net/ipv4/ip_output.c:535
l2tp_xmit_queue net/l2tp/l2tp_core.c:1007 [inline]
l2tp_xmit_core net/l2tp/l2tp_core.c:1093 [inline]
l2tp_xmit_skb+0x93a/0x1940 net/l2tp/l2tp_core.c:1109
pppol2tp_sendmsg+0x3f2/0x5e0 net/l2tp/l2tp_ppp.c:318
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0xd5/0x180 net/socket.c:745
sock_write_iter+0x29b/0x3d0 net/socket.c:1160
call_write_iter include/linux/fs.h:2085 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0x6d5/0x1100 fs/read_write.c:590
ksys_write+0x1f0/0x250 fs/read_write.c:643
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x79/0x110 arch/x86/entry/common.c:321
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:346
entry_SYSENTER_compat_after_hwframe+0x70/0x7a
RIP: 0023:0xf7f5d579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f7f585ac EFLAGS: 00000292 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000020000840
RDX: 0000000000000573 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 10 06 adc %al,(%rsi)
2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi
6: 10 07 adc %al,(%rdi)
8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
c: 10 08 adc %cl,(%rax)
e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
1e: 00 51 52 add %dl,0x52(%rcx)
21: 55 push %rbp
22: 89 e5 mov %esp,%ebp
24: 0f 34 sysenter
26: cd 80 int $0x80
* 28: 5d pop %rbp <-- trapping instruction
29: 5a pop %rdx
2a: 59 pop %rcx
2b: c3 ret
2c: 90 nop
2d: 90 nop
2e: 90 nop
2f: 90 nop
30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi